If the vandal is an admin, then protecting the page won't do anything. You need to try to talk it out with the admin. If that doesn't work, talk to a bureaucrat. If they are a bureaucrat, then it now becomes a community issue whether or not that person should be demoted; which would require the help of Fandom staff.
@Jeehutanic are you an admin at the wiki where the page you want to protect lives? It would help us more if you gave us a link to the profile page of the person you want to protect the pages from on that wiki.